A new way to measure light using a superconducting detector has been unveiled by physicists at NASA’s Jet Propulsion Laboratory and the California Institute of Technology, both in Pasadena, CA. The technology exploits the characteristics of superconductivity and has a number of properties that should lead to uses in a variety of fields, from medicine to astrophysics.
Scientists have known for some time that superconductors function as they do because of electrons in the material being linked together as ‘Cooper pairs’ with a binding energy just right to allow current to flow with no resistance. If the material is heated above a certain temperature, the Cooper pairs are torn apart by thermal fluctuations, and the result is electrical resistance.
The researchers, JPL researchers Drs. Peter Day and Henry LeDuc, along with Dr. Jonas Zmuidzinas, a Caltech physics professor, designed their superconducting device to register the slight changes that occur when an incoming photon interacts with the material and affects the Cooper pairs. The device can be made sensitive enough to detect individual photons, as well as their wavelengths or colour.
The individual frequencies of the photons can also be measured very accurately with this method, which should provide a significant benefit to astrophysicists, as well as researchers in a number of other fields, Zmuidzinas said.
‘In astrophysics, this will give you lots more information from every photon you detect,’ he explained. ‘There are single-pixel detectors in existence that have similar sensitivity, but our new detector allows for much bigger arrays (to be built), potentially with thousands of pixels.’
Such detectors could provide an accurate means of measuring the fine details of the cosmic microwave background radiation, which is the relic of the intense light that filled the early universe. It’s detectable today as an almost uniform glow of microwave radiation coming from all directions.
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